The present invention relates to a process and to an apparatus for producing a strain-free monocrystal of a ferroelectric compound having a crystalline structure. It more particularly applies to the production of lithium niobate (LiNbO.sub.3) strain-free monocrystals, used e.g. in the production of surface wave filters, modulators and optical amplifiers.
The known processes and apparatuses for producing monocrystals of crystalline ferroelectric compounds have the disadvantage of producing, in the case of certain ferroelectric compounds and particularly lithium niobate, monocrystals having internal strains which produce fractures and the probability of fracture formation increases with the length of the monocrystal.